Composite structure formation method, pre-formed controlled particles formed of fine particles non-chemically bonded together, and composite structure formation system involving controlled particles

ABSTRACT

A composite structure formation method includes the steps of storing a plurality of pre-formed controlled particles in a storage mechanism, supplying the controlled particles from the storage mechanism to an aerosolation mechanism constantly, disaggregating the supplied controlled particles into a plurality of the fine particles in the aerosolation mechanism to form an aerosol in which an entire contents of the controlled particles including the fine particles are dispersed in the gas; and spraying all of the fine particles in the aerosol toward the substrate to form a composite structure of the structure and the substrate. The controlled particles are controlled so that bonding strength between the fine particles includes a mean compressive fracture strength sufficient to substantially avoid disaggregation during the supply step, but which permits the controlled particles to be substantially completely disaggregated in the disaggregation step.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 13/544,059, filed on Jul. 9, 2012, which is adivisional application of the U.S. patent application Ser. No.12/381,225, filed on Mar. 9, 2009, which is based upon and claims thebenefit of priority from the prior Japanese Patent Application No.2008-060189, filed on Mar. 10, 2008, the prior Japanese PatentApplication No. 2009-053493, filed on Mar. 6, 2009, and the prior U.S.Provisional Application 61/055,469, filed on May 23, 2008. The entirecontents of these prior applications are incorporated herein byreference.

BACKGROUND OF THE INVENTION

Field of the Invention

This invention generally relates to a composite structure formationmethod based on the aerosol deposition method by which an aerosol withfine particles of a brittle material dispersed in a gas is sprayed ontoa substrate to form a structure made of the fine particles on thesubstrate, a controlled particle for use therein, and a compositestructure formation system.

Description of the Related Art

The “aerosol deposition method” is one of the methods for forming astructure made of a brittle material on the surface of a substrate (see,e.g., Japanese Patent No. 3348154, JP-A-2006-200013(Kokai), andJP-A-2006-233334(Kokai)). In this method, an aerosol in which fineparticles including a brittle material are dispersed in a gas is sprayedfrom a discharge port toward the substrate to collide the fine particleswith the metal, glass, ceramic, or plastic substrate, deforming orfracturing the brittle material fine particles by the impact of thiscollision to join them together, so that a film-like structure made ofthe fine particles is directly formed on the substrate. This method canform a film-like structure at normal temperature without requiring anyspecific heating means and the like, and can provide a film-likestructure having a mechanical strength which is at least comparable tothat of a sintered body. Furthermore, the condition for colliding thefine particles as well as the shape, composition and the like of thefine particles can be controlled to diversely vary the density,mechanical strength, electrical characteristics and the like of thestructure.

To form a large-area film-like structure by this aerosol depositionmethod, fine particles need to be continuously supplied for a prescribedperiod of time. In particular, in the case where a high film thicknessaccuracy is required, it is desired that the supply quantity of fineparticles be constantly stable.

However, as disclosed in Japanese Patent No. 3348154, if aerosolationoccurs in a storage mechanism which stores fine particles of a rawmaterial, the fine particles stored in the storage mechanism may changethe state over time, leaving a problem with stable supply of theaerosol. Furthermore, the capacity of the storage mechanism needs to befar larger than the volume of fine particles to secure the capacity foraerosolation, which may require a large-scale apparatus.

In this context, in the technique proposed in JP-A-2006-200013(Kokai),the storage mechanism for storing fine particles is separated from theaerosolation mechanism for mixing the fine particles with a gas toproduce an aerosol, and the fine particles are supplied from the storagemechanism to the aerosolation mechanism by required amount.

However, in the case where submicron or smaller fine particles are usedas primary particles, because of their high viscosity and adhesiveness,the problems of adhesion, stacking and the like to the wall surface arelikely to occur inside the storage mechanism and in the process ofsupply from the storage mechanism to the aerosolation mechanism, whichmay make it difficult to supply reliably. For example, fine particlesare likely to aggregate due to agitation and migration inside thestorage mechanism and change their fluidity. Eventually, stacking occursinside the storage mechanism and prevents migration of powder to theaerosolation mechanism, which may lose the constancy of the supplyquantity. Furthermore, adhesion occurring inside the storage mechanismmay also yield adverse effects, such as failing to achieve powder usageas planned.

In this regard, in the technique proposed in JP-A-2006-233334(Kokai), asplit supply mechanism for supplying fine particles from the storagemechanism to the aerosolation mechanism is provided, and the fineparticles stored in the storage mechanism are split into a plurality ofgroups and supplied by the split supply mechanism.

However, the following problems may occur in the case where a batch ofbrittle material fine particle powder stored in the storage mechanism issplit into a plurality of groups and supplied by the split supplymechanism. Originally, the brittle material fine particle powder storedin the storage mechanism is not controlled in density and lacksuniformity in fluidity. Accordingly, the group of fine particles splitin a prescribed size and shape may be nonuniform in shape and densitywhen supplied from the storage mechanism. In some cases, the trouble ofstacking of brittle material fine particle powder occurs in the storagemechanism. In such cases, even using an aerosolation mechanism having aprescribed disaggregation capability, it is difficult to generate anaerosol with a constantly stable fine particle concentration.Furthermore, if the group of fine particles split in a prescribed sizeand shape changes in shape or density during the supply process, it maybe also difficult to accurately control the fine particle concentrationin the aerosol. Moreover, at low density, the shape may collapse duringthe supply and cause fine particles to adhere to the inner wall of theapparatus, impairing constancy of quantity.

Patent Document: Japanese Patent No. 3348154

Patent Document: JP-A-2006-200013 (Kokai)

Patent Document: JP-A-2006-233334 (Kokai)

SUMMARY OF THE INVENTION

According to an aspect of the invention, there is provided a compositestructure formation method based on an aerosol deposition method bywhich an aerosol with brittle material fine particles dispersed in a gasis sprayed toward a substrate to form a structure made of the brittlematerial fine particles, the composite structure formation methodincluding: storing a plurality of controlled particles in a storagemechanism, the controlled particle being an assembly packed with aplurality of particles including the brittle material fine particles;supplying the controlled particles from the storage mechanism to anaerosolation mechanism; disaggregating the supplied controlled particlesin the aerosolation mechanism to form an aerosol; and spraying theaerosol toward the substrate to form a composite structure having thestructure and the substrate.

According to another aspect of the invention, there is provided acontrolled particle for use in an aerosol deposition method by which anaerosol with brittle material fine particles dispersed in a gas issprayed toward a substrate to form a structure made of the brittlematerial fine particles, the controlled particle including: an assemblypacked with a plurality of particles including the brittle material fineparticles having a mean primary particle diameter of 0.1 μm or more and5 μm or less.

According to another aspect of the invention, there is provided acomposite structure formation system for use in an aerosol depositionmethod by which an aerosol with brittle material fine particlesdispersed in a gas is collided with a substrate to form a compositestructure having the substrate and a structure made of the brittlematerial fine particles, the composite structure formation systemincluding: a storage mechanism configured to store controlled particlesfor use in an aerosol deposition method by which an aerosol with brittlematerial fine particles dispersed in a gas is sprayed toward a substrateto form a structure made of the brittle material fine particles, thecontrolled particles including: an assembly packed with a plurality ofparticles including the brittle material fine particles having a meanprimary particle diameter of 0.1 μm or more and 5 μm or less; a supplymechanism configured to supply the controlled particles from the storagemechanism; a gas supply mechanism configured to introduce a gas towardthe supplied controlled particles; an aerosolation mechanism configuredto apply an impact to the controlled particles mixed with the gas todisaggregate the controlled particles and form an aerosol; and adischarge port configured to spray the aerosol onto the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1C are schematic views for illustrating the basicconfiguration of a composite structure formation system according to afirst embodiment of the invention;

FIG. 2 is a graph for illustrating the measurement of compressivefracture strength;

FIG. 3 is a graph for illustrating the relationship between meancompressive fracture strength and composite structure formation;

FIG. 4 is a graph for illustrating the histogram in the distribution ofcontrolled particles;

FIG. 5 is a graph for illustrating the relationship between a meancircle-equivalent diameter and supply quantity standard deviation;

FIG. 6 is a graph for illustrating the relationship between meancircularity and supply quantity standard deviation;

FIG. 7 is a graph for illustrating the relationship between meancircularity and supply quantity standard deviation in the case where thesupply rate is 0.5 g/min;

FIG. 8 is a graph for illustrating the relationship between meancircularity and supply quantity standard deviation in the case where thesupply rate is 5 g/min;

FIG. 9 is a graph for illustrating the relationship between D10 valueand supply quantity standard deviation;

FIG. 10 is a graph for illustrating the relationship between particlesize distribution deviation ratio and supply quantity standarddeviation;

FIG. 11 is a graph for illustrating the relationship between angle ofrepose and supply quantity standard deviation;

FIG. 12 is a graph for illustrating the relationship between angle ofrepose and supply quantity standard deviation in the case where thesupply rate is 0.5 g/min;

FIG. 13 is a graph for illustrating the relationship between angle ofrepose and supply quantity standard deviation in the case where thesupply rate is 5 g/min;

FIGS. 14A to 14C are schematic views for illustrating the basicconfiguration of a composite structure formation system according to asecond embodiment of the invention;

FIGS. 15A to 15C are schematic views for illustrating the basicconfiguration of a composite structure formation system according to athird embodiment of the invention;

FIG. 16 is a schematic view for illustrating a first example of thecomposite structure formation system according to the embodiment of theinvention;

FIG. 17 is a schematic view for illustrating a second example of thecomposite structure formation system according to the embodiment of theinvention;

FIG. 18 is a schematic view for illustrating a third example of thecomposite structure formation system according to the embodiment of theinvention;

FIGS. 19 to 21 are schematic views for illustrating measuring mechanismswhich can be used in this embodiment;

FIG. 22 is a schematic view for illustrating a first example of theconstant supply mechanism 2;

FIG. 23 is a schematic view for illustrating a second example of theconstant supply mechanism 2;

FIG. 24 is a schematic view for illustrating a third example of theconstant supply mechanism 2;

FIG. 25 is a schematic view for illustrating a fourth example of theconstant supply mechanism 2;

FIG. 26 is a schematic view for illustrating a fifth example of theconstant supply mechanism 2;

FIG. 27 is a schematic view for illustrating a sixth example of theconstant supply mechanism 2;

FIG. 28 is a schematic view for illustrating a seventh example of theconstant supply mechanism 2;

FIG. 29 is a schematic view for illustrating an eighth example of theconstant supply mechanism 2;

FIG. 30 is a schematic view for illustrating a ninth example of theconstant supply mechanism 2;

FIG. 31 is a schematic view for illustrating a first example of theaerosolation mechanism;

FIG. 32 is a schematic view for illustrating a second example of theaerosolation mechanism;

FIG. 33 is a schematic view for illustrating a third example of theaerosolation mechanism;

FIG. 34 is a schematic view for illustrating a fourth example of theaerosolation mechanism; and

FIG. 35 is a schematic view for illustrating a fifth example of theaerosolation mechanism.

DETAILED DESCRIPTION OF THE INVENTION

Before the description of embodiments of the invention, terms usedherein are first described.

The term “fine particle” as used herein refers to a particle formed bychemical bonding of brittle material crystals. This fine particle usedin the aerosol deposition method illustratively includes those having amean primary particle diameter of 0.1 μm or more and 5 μm or less asdescribed in Japanese Patent No. 3348154. Here, determination of themean primary particle diameter can be based on the method of calculatinga circle-equivalent diameter from the image of a plurality of (desirably50 or more) brittle material fine particles obtained by electronmicroscopic observation.

“Primary particle” refers to the minimum unit (single particle) of thefine particle.

“Controlled particle” refers to an assembly packed with a plurality ofparticles including brittle material fine particles having a meanprimary particle diameter of 0.1 μm or more and 5 μm or less. That is,the controlled particle is formed through the step of artificialcompaction.

The controlled particle keeps its shape by physical attraction force(static electricity, van der Waals force, and cross-linking attractionof water) as main bonding force, and at least one of the bondingstrength and shape is intentionally controlled. Alternatively, thecontrolled particle keeps its shape by attraction force such that itcollapses by irradiation of supersonic waves in water as main bondingforce, and at least one of the bonding strength and shape isintentionally controlled.

Compressive fracture strength of the controlled particle can serve as anindicator of its bonding strength.

Circularity can serve as an indicator of the shape of the controlledparticle.

Preferably, the controlled particle is intentionally controlled in itsdiameter. A mean circle-equivalent diameter of the controlled particlecan serve as an indicator of its diameter.

Preferably, the controlled particles are intentionally controlled intheir particle diameter distribution. D10 or particle size distributiondeviation ratio can serve as an indicator of the particle diameterdistribution of the controlled particles.

Preferably, in the controlled particle, brittle material fine particlescontained therein are not compacted, by chemical bonding therebetween,to a size which is significantly larger than the diameter of the primaryparticle. The brittle material fine particles chemically bonded to eachother refer to what looks like a primary particle of a porous materialin which fine particles are fused together at their surfaces under heattreatment and the like to cause neck formation. Although this can beidentified by electron microscopic observation, the existence ofchemical bonding can be concluded if a collection of a plurality of fineparticles is put into water or an alcohol solvent, for example, and itis not dispersed or easily collapsed. In the case where primaryparticles are compacted in units of several particles, the fine particlediameter may be allowable for structure formation in the aerosoldeposition method, and there is no significant problem even if particlesin such a state are actually included. This state can also be identifiedby electron microscopic observation of brittle material fine particleswhich are sufficiently dispersed and fixed on the observation stage.

“Aggregate particle” refers to a collection of a plurality of fineparticles which is spontaneously formed from the fine particles bondedto each other, where its bonding strength and shape are not controlled.

“Disaggregation” refers to an action on the controlled particle, inwhich particles composed primarily of brittle material fine particlesare compacted by physical attraction, to separate the individual brittlematerial fine particles by applying external force such as impact,friction, vibration, and charging. Here, the disaggregation does notneed to separate all the primary particles to the monodisperse state,but as described later, the disaggregation only needs to ensure aseparation state allowing structure formation with industrialapplicability.

That the controlled particles being supplied from the storage containerare not disaggregated can be determined by measuring the stability ofthe supply quantity of controlled particles over time or by comparingthe shape of the controlled particle in the storage container with thatimmediately before aerosolation.

Here, if the controlled particles are disaggregated when supplied fromthe storage container, brittle material fine particles dropped off fromthe controlled particles are adhered to the storage container and theaerosolation mechanism where the controlled particles are brought intocontact, causing clogging at such contact sites. This hampers migrationof the controlled particles, and the supply quantity tends to vary overtime.

That the controlled particles are disaggregated in the aerosolationmechanism can be determined by comparing by observation the shape andstate of the controlled particle immediately before aerosolation withthose of the controlled particle immediately after aerosolation.

Here, disaggregation can be affirmed by verifying the state change inwhich the number of controlled particles clearly decreases and primaryparticles included therein emerge frequently. For example,disaggregation can be affirmed if the ratio of the number of controlledparticles in a certain weight of controlled particles afterdisaggregation to that in the same weight before the disaggregation isone fifth or less, preferably one tenth or less, and more preferably onehundredth or less. These can be verified illustratively by opticalmicroscopic observation.

“Aerosol” refers to a solid-gas mixed phase composition in which fineparticles are dispersed in a gas such as helium, nitrogen, argon,oxygen, dry air, and a mixed gas including them, where substantiallymost of the fine particles are dispersed nearly separately, although theaerosol may partly include aggregate particles. The gas pressure andtemperature of the aerosol are arbitrary. However, the concentration offine particles in the gas at the point of being sprayed from a dischargeport, in terms of the value at a gas pressure of 1 atmosphere and atemperature of 20 degrees Celsius, is preferably in the range from0.0003 to 10 mL/L for forming a film-like structure.

“Solid-gas mixed phase flow” refers to the state in which controlledparticles controlled to a prescribed bonding strength or shape aremigrating on a gas flow. In the solid-gas mixed phase flow, thecontrolled particles exist substantially separately in the gas flow.

“Solid phase” refers to the state in which controlled particles arenearly independent of the gas flow.

“Stacking” refers to the prevention of particle migration in a containeror a channel traversed by particles due to adhesion of particles oraggregation of the particles themselves, or to the state in which itoccurs. Stacking is likely to occur at a location where thecross-sectional shape of the channel traversed by particles isdownsized, such as the outlet of the storage mechanism, the inlet of thesupply mechanism, and the supply channel, described later.

Next, embodiments of the invention are described with reference to thedrawings.

FIG. 1 is a schematic view for illustrating the basic configuration of acomposite structure formation system according to a first embodiment ofthe invention. More specifically, FIG. 1A is a block diagram forillustrating the basic configuration of a composite structure formationsystem (aerosol deposition apparatus), FIG. 1B schematically shows theprocess flow from storage to aerosolation of controlled particles, andFIG. 1C shows state changes in the process from storage to aerosolationof controlled particles. Here, FIGS. 1B and 1C are depicted so as tocorrespond to the components shown in FIG. 1A.

As shown in FIG. 1A, the composite structure formation system (aerosoldeposition apparatus) 100 according to this embodiment includes astorage mechanism 1, a constant supply mechanism 2, a gas supplymechanism 3, an aerosolation mechanism 4, and a discharge port 5.

The constant supply mechanism 2 is provided at the subsequent stage ofthe storage mechanism 1. The aerosolation mechanism 4 is provided at thesubsequent stage of the constant supply mechanism 2, and the dischargeport 5 is provided at the subsequent stage of the aerosolation mechanism4. The gas supply mechanism 3 is connected near the outlet of theconstant supply mechanism 2.

The storage mechanism 1 stores controlled particles 31 which are formedin advance. The constant supply mechanism 2 supplies the subsequentaerosolation mechanism 4 with a prescribed quantity of controlledparticles 31 stored in the storage mechanism 1 without impairing theshape and state of the controlled particles 31. The constant supplymechanism 2 may be under feedback control as described later so that thesupply quantity can be stabilized or varied over time. The controlledparticle 31 is described later in detail.

In combination with a gas G supplied by the gas supply mechanism 3, thecontrolled particles 31 supplied by the constant supply mechanism 2 forma solid-gas mixed phase flow 33, which is supplied to the aerosolationmechanism 4 through a supply channel 16. The supplied controlledparticles 31 are disaggregated in the aerosolation mechanism 4, and fineparticles 30P are dispersed in the gas G to form an aerosol 32. Thisaerosol 32 is sprayed from the discharge port 5 toward a substrate, notshown, and a film-like structure (see FIG. 16) is formed on thesubstrate.

Alternatively, as described later, it is also possible to supplycontrolled particles 31 to the aerosolation mechanism 4, disaggregatethe supplied controlled particles 31 in the aerosolation mechanism 4,and use a gas G supplied from the gas supply mechanism 3 to theaerosolation mechanism 4 to form an aerosol 32 in which fine particles30P are dispersed in the gas G (see FIG. 15).

However, if the solid-gas mixed phase flow 33 is formed, it serves notonly to supply controlled particles 31, but also to accelerate thecontrolled particles 31 toward the aerosolation mechanism 4. Hence,disaggregation by mechanical impact using the kinetic energy of theaccelerated controlled particles 31 facilitates aerosolation.

The gas supply mechanism 3 may be connected to the storage mechanism 1and the constant supply mechanism 2 to reliably supply controlledparticles 31 to the aerosolation mechanism 4, and may be connected tothe aerosolation mechanism 4 and the supply channel between theaerosolation mechanism 4 and the discharge port 5, for example, toadjust the fine particle concentration in the aerosol. The connectiondestination and the combination of connections of the gas supplymechanism 3 can be suitably modified.

Here, the principle of the aerosol deposition method is described.

Fine particles used in the aerosol deposition method are composedprimarily of a brittle material. Here, fine particles of a singlematerial property can be used alone, or fine particles having differentparticle diameters can be mixed.

The fine particle can be illustratively made of a brittle material suchas oxides composed primarily of aluminum oxide, titanium oxide, zincoxide, tin oxide, iron oxide, zirconium oxide, yttrium oxide, chromiumoxide, hafnium oxide, beryllium oxide, magnesium oxide, silicon oxide,calcium oxide, lanthanum oxide, strontium oxide, tantalum oxide, bariumoxide, cobalt oxide, copper oxide, gadolinium oxide, indium oxide,lithium oxide, molybdenum oxide, manganese oxide, niobium oxide, nickeloxide, osmium oxide, lead oxide, palladium oxide, praseodymium oxide,ruthenium oxide, antimony oxide, scandium oxide, terbium oxide, vanadiumoxide, tungsten oxide, ytterbium oxide or the like or composite oxidesthereof, diamond, carbides such as boron carbide, silicon carbide,titanium carbide, zirconium carbide, vanadium carbide, niobium carbide,chromium carbide, tungsten carbide, molybdenum carbide, and tantalumcarbide, nitrides such as boron nitride, titanium nitride, aluminumnitride, silicon nitride, niobium nitride, and tantalum nitride, boron,borides such as aluminum boride, silicon boride, titanium boride,zirconium boride, vanadium boride, niobium boride, tantalum boride,chromium boride, molybdenum boride, and tungsten boride, or mixtures,multicomponent solid solutions, or compounds thereof, compositeoxide-based piezoelectric or pyroelectric ceramics such as bariumtitanate, lead titanate, lithium titanate, strontium titanate, aluminumtitanate, PZT, and PLZT, high-toughness ceramics such as sialon andcermet, biocompatible ceramics such as hydroxyapatite and calciumphosphate, semiconductor materials such as silicon and germanium, andthese materials doped with various dopants such as phosphorus, compoundssuch as gallium arsenide, indium arsenide, cadmium sulfide, and zincsulfide, or composite materials composed primarily of these materials incombination with a metal or resin.

Furthermore, it is also possible to use a mixture or composite ofdifferent kinds of brittle material fine particles. Furthermore, thebrittle material fine particles can be mixed with fine particles of ametal material, organic material or the like, or the surface of thebrittle material fine particle can be coated therewith. However, even inthese cases, the film-like structure is composed primarily of a brittlematerial.

The gas G can illustratively be air, hydrogen gas, nitrogen gas, oxygengas, argon gas, helium gas, or other inert gas, or an organic gas suchas methane gas, ethane gas, ethylene gas, and acetylene gas, or acorrosive gas such as fluorine gas. Furthermore, a mixed gas thereof maybe used as needed.

The process of the aerosol deposition method is typically performed atnormal temperature, and characterized, in one aspect, in that afilm-like structure can be formed at a temperature sufficiently lowerthan the melting point of the fine particle material, that is, atseveral hundred degrees Celsius or less.

In the case where fine particles of a crystalline brittle material areused as a raw material, the film-like structure portion of the compositestructure formed by the aerosol deposition method is composed ofpolycrystals in which the crystal particle size thereof is smaller thanthat of the raw material fine particle, and the crystal often lackssubstantial crystalline orientation. Furthermore, no substantial grainboundary layer made of a glass layer exists at the interface between thebrittle material crystals. Furthermore, the film-like structure portionoften includes an “anchor layer” which bites into the surface of thesubstrate. Because of this anchor layer, the film-like structure formedis robustly adhered to the substrate with very high strength.

The film-like structure formed by the aerosol deposition method hassufficient strength, being clearly different from the so-called “greencompact” in which fine particles are packed together by pressure andkeep shape by physical adhesion.

Here, that incoming brittle material fine particles have deformed orcrushed on the substrate in the aerosol deposition method can beverified by measuring the crystallite size of the brittle material fineparticle used as a raw material and the formed brittle materialstructure by X-ray diffractometry and the like.

The crystallite size of the film-like structure formed by the aerosoldeposition method is smaller than the crystallite size of the rawmaterial fine particle. Furthermore, a “new surface”, where atomsoriginally located inside the fine particle and bonded to other atomsare exposed, is formed at the “shear surface” and “fracture surface”formed by crush and deformation of the fine particle. It is consideredthat this new surface, having high surface energy and being active,joins with the surface of an adjacent brittle material fine particle,the new surface of an adjacent brittle material, or the surface of thesubstrate to form a film-like structure.

Furthermore, if a proper quantity of hydroxy groups exist at the surfaceof fine particles in the aerosol, it is considered that, at the time ofcollision of the fine particle, local shear stress and the like betweenfine particles or between the fine particle and the structure causemechanochemical acid-base dehydration reaction, which joins themtogether. It is considered that continuous external application ofmechanical impact force successively causes these phenomena, andrepeated deformation, fracture and the like of fine particles developjunctions and densify, growing a film-like structure made of the brittlematerial.

To disaggregate the controlled particle 31 in the aerosolation mechanism4, mechanical impact force produced by colliding the controlled particle31 with a wall, protrusion, rotating body or the like is useful. Inparticular, acceleration in the state of the solid-gas mixed phase flow33 in which the controlled particles 31 are mixed with a gas Gfacilitates colliding the controlled particles 31 having some mass witha wall or the like by inertial force. Here, the disaggregation energydepends on the mass and velocity of the controlled particle 31. To gaina velocity required for disaggregation, a pressure difference isrequired between before and after (inlet side and outlet side) of theaerosolation mechanism 4.

On the basis of the inventors' findings, if the gas used isillustratively one of air, nitrogen, and oxygen, or a mixed gas composedprimarily of the aforementioned gas, and the supply quantity of the gasfor the minimum cross-sectional area of the supply channel has a volumeflow rate of 0.05 L/(min·mm²) or more and 50.0 L/(min·mm²) or less interms of the value at 1 atmosphere and 25° C., then the controlledparticles 31 in the solid-gas mixed phase flow can be efficientlyaccelerated, and aerosolation can be reliably and readily performed.

Here, in the aerosol deposition method, to produce a film-like structurebeing homogeneous over a large area and having a uniform thickness, thefine particle concentration in the sprayed aerosol needs to beconstantly stable. That is, how to form an aerosol having a stable fineparticle concentration is an important technical factor of this methodin stabilizing the quality and grade of the film.

In this regard, in the technique as disclosed in Japanese Patent No.3348154, the state of fine particles stored in the storage mechanismchanges over time, for example, which may make it difficult to generatean aerosol having a stable fine particle concentration.

Likewise, in the technique as disclosed in JP-A-2006-200013(Kokai), inthe case where submicron or smaller fine particles are used as primaryparticles, because of their high viscosity and adhesiveness, theproblems of adhesion, stacking and the like to the wall surface arelikely to occur inside the storage mechanism and in the process ofsupply from the storage mechanism to the aerosolation mechanism, whichmay make it difficult to generate an aerosol having a stable fineparticle concentration.

Furthermore, also in the technique as disclosed inJP-A-2006-233334(Kokai), which can form an aerosol having the moststable fine particle concentration, the fine particle or the group offine particles split in a prescribed size and shape may be nonuniform inshape and density when supplied from the storage mechanism or in theprocess of supply to the aerosolation mechanism. This may make itdifficult, although instantaneously, to form an aerosol having a stablefine particle concentration. For example, when supplied from the storagemechanism or in the process of supply to the aerosolation mechanism, thegroups of fine particles are partly disaggregated and adhered to thewall surface, which may make it difficult, although instantaneously, toform an aerosol having a stable fine particle concentration.

As a result of studies by the inventors, it has been found that ifcontrolled particles, each being an assembly packed with a plurality ofparticles including brittle material fine particles having a meanprimary particle diameter of 0.1 μm or more and 5 μm or less, areproduced in advance and supplied from the storage mechanism to theaerosolation mechanism, then the supply can be made uniform and stable.Furthermore, it has also been found that constant supply capability canbe enhanced by intentionally controlling at least one of the bondingstrength and shape of the controlled particle.

As described above, the brittle material fine particles having aparticle diameter of 0.1 μm or more and 5 μm or less have highaggregability and, if used directly, exhibit very poor handleability.Furthermore, they often form an aggregate particle. Even if such brittlematerial fine particles are supplied by mechanical means, it is verydifficult to ensure constancy of quantity. Hence, in forming an aerosolin the aerosol deposition method, there is a problem of being difficultto ensure temporal uniformity and stability in the aerosolconcentration.

In this regard, if controlled particles, each being an assembly packedwith a plurality of particles including brittle material fine particleshaving a mean primary particle diameter of 0.1 μm or more and 5 μm orless, are produced in advance, and fine particles having high viscosityand adhesiveness are accordingly supplied, then disaggregation in thesupply process and adhesion, stacking and the like associated therewithcan be prevented, and hence constant supply capability can be enhanced.

Furthermore, disaggregation can be substantially prevented also in theprocess of supply from the storage mechanism 1 by the constant supplymechanism 2, and hence constant supply capability can be enhanced.

Furthermore, constant supply capability can be further enhanced byintentionally controlling at least one of the bonding strength and shapeof the controlled particle.

Thus, in the aerosolation mechanism 4 provided at the subsequent stage,the fine particle concentration does not significantly vary also in ashort period of time, and it is possible to form an aerosol having afine particle concentration which is uniform over time and stable in along period of time. Consequently, the quantity of fine particles in theaerosol sprayed from the discharge port can be accurately controlled.Hence, the thickness and quality of the film-like structure formed onthe substrate can be precisely controlled.

Next, the inventors' findings about the controlled particle 31 aredescribed.

The mean compressive fracture strength of the controlled particle 31 canserve as an indicator in enhancing constant supply capability, aerosolconcentration uniformity and the like.

For example, if the mean compressive fracture strength is too low, whensupplied from the storage mechanism 1 or in the process of supply to theaerosolation mechanism 4, the controlled particle 31 is disaggregatedand adhered to the wall surface, which may decrease constant supplycapability, aerosol concentration uniformity and the like. On the otherhand, if the mean compressive fracture strength is too high, althoughconstant supply capability can be ensured, it interferes withdisaggregation in the aerosolation mechanism 4, and may decrease aerosolconcentration uniformity and the like. Thus, the mean compressivefracture strength of the controlled particle 31 is preferably in aprescribed range.

That is, the controlled particle 31 is assumed to have a meancompressive fracture strength required to substantially avoiddisaggregation when supplied from the storage mechanism 1. Furthermore,the controlled particle 31 is assumed to have a mean compressivefracture strength required to substantially avoid disaggregation in theprocess of supply to the aerosolation mechanism 4, but to besubstantially disaggregated in the aerosolation mechanism 4.

The mean compressive fracture strength is calculated as the mean valueof compressive fracture strengths measured for a plurality of (e.g., 10or more) controlled particles 31 which are arbitrarily selected.

Here, the measurement of compressive fracture strength performed by theinventors and the relationship between mean compressive fracturestrength and composite structure formation are described.

First, the measurement of compressive fracture strength is described.

Controlled particles including brittle material fine particles with amean primary particle diameter of approximately 0.3 μm and having acircle-equivalent diameter in the range from 100 to 400 μm werearranged, and measured for compressive fracture strength. Thecircle-equivalent diameter is described later.

The compressive fracture strength was measured using the Shimadzumicro-compression tester MCT-W201 manufactured by Shimadzu Corporation.The indenter used for measurement was FLAT500. As for the initialcondition, the magnification of the objective lens was ×10, the lengthmeasurement mode was “single”, and the compression ratio for referencestrength calculation was 10%. The test mode was “compression test”, thetest force was 196.1 mN, and the loading speed was 0.9 mN/sec. Thus, thecompressive fracture strength was measured for 10 controlled particles31 which were arbitrarily selected.

The compressive fracture strength was calculated by the followingformula from the test force and the particle diameter at the time whenthe controlled particle was broken by being pressed to the indenter:St=2.8P/(n×d×d)where St is the compressive fracture strength (Pa), P is the test force(N) at the time of compressive fracture, and d is the controlledparticle diameter (mm).

FIG. 2 is a graph for illustrating the measurement of compressivefracture strength. The horizontal axis represents displacement, and thevertical axis represents test force.

In this measurement of compressive fracture strength, as shown in FIG.2, the test force P at the time of compressive fracture was determinedto be the point from which the variation in the test force is nearlyconstant and only the displacement increases. The controlled particlediameter d was measured using the optical instrument provided in thecompression tester.

Next, the relationship between mean compressive fracture strength andcomposite structure formation is described.

Controlled particles having various compressive fracture strengths witha circle-equivalent diameter in the range from 100 to 400 μm werearranged, and used to form a composite structure by the aerosoldeposition method. In the apparatus used for the aerosol depositionmethod, the constant supply mechanism was a vibrating type supplyingapparatus, the aerosolation mechanism was based on collision of asolid-gas mixed phase flow with a ceramic plate, and the gas wasnitrogen.

The opening of a nozzle serving as the discharge port was 10 mm×0.4 mm,and the gas flow rate of the aerosol squirted from the opening was 5L/min. The substrate for forming a composite structure thereon was aplate of SUS304 stainless steel. The stroke for reciprocating thesubstrate was 10 mm, and the time for forming a composite structure on a10 mm×10 mm surface (aerosol spraying time) was 10 minutes.

FIG. 3 is a graph for illustrating the relationship between meancompressive fracture strength and composite structure formation. Thehorizontal axis represents mean compressive fracture strength, and thevertical axis represents the thickness of the film-like structure.

As seen from FIG. 3, at mean compressive fracture strength exceeding0.47 MPa, it is only possible to form thin films, causing a problem withproductivity. This is presumably because the excessively highcompressive fracture strength of the controlled particle interferes withdisaggregation of the controlled particle in the aerosolation mechanism.On the basis of the inventors' findings, a mean compressive fracturestrength of 0.47 MPa or less enables composite structure formation whichis preferable from the viewpoint of productivity. Furthermore, a meancompressive fracture strength of 0.34 MPa or less enables compositestructure formation which is more preferable from the viewpoint ofproductivity.

The foregoing relates to the upper bound of the mean compressivefracture strength. As seen from FIG. 3, a thick film can be formed in ashorter period of time as the mean compressive fracture strength becomeslower. Hence, the lower bound cannot be determined from the viewpoint ofproductivity.

As described above, the lower bound of the mean compressive fracturestrength is determined primarily from the viewpoint of constant supplycapability. More specifically, if the mean compressive fracture strengthis too low, when supplied from the storage mechanism or in the processof supply to the aerosolation mechanism 4, even under the condition forgentle feed, the controlled particle may be disaggregated, or part ofthe brittle material fine particles constituting the controlled particlemay drop off from the surface, in response to various forces generatedduring the migration of particles, such as friction between controlledparticles, contact stress therebetween, and friction with the wallsurface. If the brittle material fine particles resulting fromdisaggregation and drop-off are adhered to the wall surface, migrationof controlled particles is prevented, and constant supply capability isimpaired. Hence, the mean compressive fracture strength is preferablyabove a prescribed value.

As a result of detailed studies on, for example, the types of theconstant supply mechanism 2 (e.g., sieve shaking type, supplying typebased on a turntable, supplying type based on supersonic vibration orelectromagnetic vibration, screw feeder, electrostatic supplying type,etc.) and the supply condition in the supply channel 16 and the like,the inventors have found that the mean compressive fracture strength ispreferably 0.015 MPa or more from the viewpoint of constant supplycapability.

Thus, the mean compressive fracture strength is preferably 0.46 MPa orless, and more preferably 0.34 MPa or less. Furthermore, the meancompressive fracture strength is preferably 0.015 MPa or more.

Furthermore, the mean circle-equivalent diameter of the controlledparticle 31 can serve as an indicator in enhancing constant supplycapability, aerosol concentration uniformity and the like.

For example, if the mean circle-equivalent diameter is too small,aggregation is more likely to occur, which may impair constant supplycapability, aerosol concentration uniformity and the like. On the otherhand, if the mean circle-equivalent diameter is too large, clogging inthe supply channel 16 and the like and disaggregation failure in theaerosolation mechanism 4 may occur. Thus, the mean circle-equivalentdiameter of the controlled particle 31 is preferably in a prescribedrange.

Here, the circle-equivalent diameter refers to the diameter of anequivalent circle having an area equal to the area of the controlledparticle 31 based on image analysis. The circle-equivalent diameter canbe calculated by analyzing the optical micrograph or the like of thecontrolled particle 31 using commercially available shape analysissoftware. Such software illustratively includes analysis software(WinROOF manufactured by Mitani Corporation) incorporated in apolarization optical microscope (LV-IMA manufactured by NikonCorporation).

The mean circle-equivalent diameter is calculated as the mean value ofcircle-equivalent diameters measured for a plurality of controlledparticles which are arbitrarily selected. In the calculation, first, asilicon wafer or the like, which has a mirror surface free from flawsresulting in noise, is prepared as a substrate for spreading controlledparticles thereon. Next, prepared fine particles to be measured on thephotographic determination image are scattered thereon. Here, they arescattered so that their area ratio occupying the photographicdetermination image is 40% or less. Then, aggregate particles andprimary particles which are not characterized as controlled particles,and groups of particles observed in the overlapping state of a pluralityof primary particles, are excluded as much as possible. The scatteredcondition of avoiding mutual overlap is ensured particularly for fineparticles around the center particle diameter. In photographicdetermination, the group of data for controlled particles with poorconstant supply capability measured at a mean circle-equivalent diameterof 5 μm or less, which is of course determined to be insufficient forthe controlled particle, is deleted. In the photographic determinationimage, the data of particles in contact with the outer peripheralboundary of the image, that is, the data of particles which are notcompletely captured in the image, are also deleted to ensure reliabilityin the value.

Furthermore, for example, as shown in FIG. 4, the distribution ofcontrolled particles having an observed mean circle-equivalent diameterof 5 μm or more is evenly divided between the minimum diameter and themaximum diameter into 10 to 20 data intervals to create a histogram.Here, in the case where there is a peak at a value of 100 μm or more andthere is another peak at a value of 30 μm or less, it is known thatthese particles with 30 μm or less hardly affect the supply quantitystandard deviation even if they account for up to approximately 80% innumber frequency. This is presumably because constant supply capabilityis governed by relatively large controlled particles, which account fora large proportion in terms of volume.

It is considered that such microparticles include fragments formed bypartly dropping off from controlled particles and those being incompletein controlled particle formation. Thus, if the distribution can beclearly determined to have a peak of controlled particles having a largeparticle diameter, which are targeted for calculation, in combinationwith another peak of microparticles out of the calculation target, thenin determining a mean circle-equivalent diameter, the group of particlesconstituting the peak of microparticles is excluded to calculate a meancircle-equivalent diameter.

Preferably, by such careful selection operation, 150 to 200 controlledparticles to be counted are selected, and their numerical values areused to determine a mean circle-equivalent diameter.

In the case where the aforementioned analysis software (WinROOFmanufactured by Mitani Corporation), for example, is used inphotographic determination, light is projected so as to ensuresufficient contrast between the substrate and the particle to beobserved. After a sufficient contrast is achieved and the focus isadjusted, a photograph is taken. The photograph taken is turned into amonochrome image and digitized.

Digitization needs care because improper setting of its thresholdresults in an erroneous value. In particular, it has significantinfluence on whether particles having a true circle-equivalent diameterof approximately 20 μm or less are selected for measurement. This alsocauses significant variation in the mean circle-equivalent diameter aswell as the D10 value and the value of the particle size distributiondeviation ratio described later.

Hence, in digitization, an approximate midpoint between the peak on thesubstrate side (typically on the white side) and the peak on theparticle side (typically on the black side) in the monochrome image ispreferably selected as a threshold.

Despite such threshold selection, a plurality of peaks may often occurin the aforementioned calculated value of the mean circle-equivalentdiameter. This requires the selection operation on the count ofparticles as described above.

In evaluating constant supply capability, first, controlled particlesincluding brittle material fine particles with a mean primary particlediameter of approximately 0.3 μm and being in the aforementioned rangeof mean compressive fracture strength were arranged, and sorted by meancircle-equivalent diameters. Then, by the following method, constantsupply capability of the controlled particles for each meancircle-equivalent diameter was evaluated.

To evaluate constant supply capability, a vibrating type supplyingapparatus was used. The supply rate was 5 g/min, the supply time was 30minutes, and the weight of controlled particles supplied from thevibrating type supplying apparatus was measured using an electronicbalance. The measurement resolution of the electronic balance was 0.01g. The temporal supply quantity was measured at every 5 seconds, andsupply quantity data from after 2 minutes to after 30 minutes were usedto determine the supply quantity and the standard deviation of thesupply quantity. Here, as a result of detailed observation on thesupplying state and the like, constant supply capability was determinedas good in the case where the supply quantity standard deviation was0.01 or less. Hence, the supply quantity standard deviation 0.01 wasadopted as a pass/fail criterion.

FIG. 5 is a graph for illustrating the relationship between meancircle-equivalent diameter and supply quantity standard deviation. Thehorizontal axis represents mean circle-equivalent diameter, and thevertical axis represents supply quantity standard deviation.

As seen from FIG. 5, if the mean circle-equivalent diameter is 20 μm ormore, the supply quantity standard deviation is 0.01 or less, exhibitinggood constant supply capability. On the other hand, if the meancircle-equivalent diameter is less than 20 μm, the supply quantity isunstable over time, impairing constant supply capability.

The foregoing relates to the lower bound of the mean circle-equivalentdiameter. As seen from FIG. 5, even if the mean circle-equivalentdiameter increases, constant supply capability is not impaired. Hence,the upper bound cannot be determined by the evaluation using thevibrating type supplying apparatus.

As described above, the upper bound of the mean circle-equivalentdiameter can be determined primarily from the viewpoint of clogging inthe supply channel 16 and the like and the occurrence of disaggregationfailure in the aerosolation mechanism 4. More specifically, if the meancircle-equivalent diameter is too large, during supply from the storagemechanism or in the process of supply to the aerosolation mechanism 4,clogging and the like occur and impair constant supply capability.Furthermore, disaggregation in the aerosolation mechanism 4 alsoproduces fragments which are not disaggregated to primary particles.Such fragments do not contribute to the formation of a film-likestructure, and consequently impairs aerosol concentration uniformity.

As a result of detailed studies on, for example, the supply condition inthe supply channel 16 and the like and the disaggregation condition inthe aerosolation mechanism 4, the inventors have found that the meancircle-equivalent diameter is preferably 500 μm or less.

Thus, the mean circle-equivalent diameter is preferably 20 μm or moreand 500 μm or less.

Furthermore, the mean circularity of the controlled particle 31 canserve as an indicator in enhancing constant supply capability, aerosolconcentration uniformity and the like.

For example, if the mean circularity is too small, rolling is madedifficult, which interferes with smooth supply. This may impair constantsupply capability, aerosol concentration uniformity and the like. Hence,the mean circularity of the controlled particle 31 is preferably above aprescribed value.

Here, the circularity is determined by the following formula, and can becalculated by analyzing the optical micrograph or the like of thecontrolled particle 31 using commercially available shape analysissoftware. Such software illustratively includes analysis software(WinROOF manufactured by Mitani Corporation) incorporated in apolarization optical microscope (LV-IMA manufactured by NikonCorporation).

Circularity = 4n × (area  of  the  controlled  particle  in  the  image)/              (perimeter  of   the  controlled  particle  in  the  image)²

Here, the circularity is equal to 1 for a perfect circle. That is, themaximum circularity is equal to 1.

The mean circularity is calculated as the mean value of circularitiesmeasured for a plurality of controlled particles which are arbitrarilyselected. In the calculation, aggregate particles and primary particleswhich are not characterized as controlled particles, and groups ofparticles observed in the overlapping state of a plurality of primaryparticles, are excluded. Specifically, in photographic determination,the group of data measured at a mean circle-equivalent diameter of 5 μmor less is deleted. In the photographic determination image, the data ofparticles in contact with the outer peripheral boundary of the image,that is, the data of particles which are not completely captured in theimage, are also deleted to ensure reliability in the value.

Here, the number of counts of controlled particles used for calculationis preferably 150 to 200. Furthermore, if the particle size distributionhas a high frequency at 30 μm or less, it is preferably treatedsimilarly to the aforementioned calculation of mean circle-equivalentdiameter. In the case where the analysis software (WinROOF manufacturedby Mitani Corporation) is used, data for mean circle-equivalent diameterand circularity can be simultaneously collected.

In evaluating constant supply capability, first, controlled particlesincluding brittle material fine particles with a mean primary particlediameter of approximately 0.3 μm and being in the aforementioned rangeof mean compressive fracture strength were arranged, and sorted by meancircularities. Then, by the following method, constant supply capabilityof the controlled particles for each mean circularity was evaluated.

To evaluate constant supply capability, a vibrating type supplyingapparatus was used. The supply rate was 5 g/min, the supply time was 30minutes, and the weight of controlled particles supplied from thevibrating type supplying apparatus was measured using an electronicbalance. The measurement resolution of the electronic balance was 0.01g. The temporal supply quantity was measured at every 5 seconds, andsupply quantity data from after 2 minutes to after 30 minutes were usedto determine the supply quantity and the standard deviation of thesupply quantity. Here, as a result of detailed observation on thesupplying state and the like, constant supply capability was determinedas good in the case where the supply quantity standard deviation was0.01 or less. Hence, the supply quantity standard deviation 0.01 wasadopted as a pass/fail criterion.

FIG. 6 is a graph for illustrating the relationship between meancircularity and supply quantity standard deviation. The horizontal axisrepresents mean circularity, and the vertical axis represents supplyquantity standard deviation.

As seen from FIG. 6, if the mean circularity is 0.79 or more, the supplyquantity standard deviation is 0.01 or less, exhibiting good constantsupply capability. On the other hand, if the mean circularity is lessthan 0.79, the supply quantity is unstable over time, which may impairconstant supply capability.

The foregoing relates to the lower bound of the mean circularity. Asseen from FIG. 6, even if the mean circularity increases, constantsupply capability is not impaired. Hence, the upper bound of the meancircularity can be set to 1 (perfect circle).

Thus, the mean circularity is preferably 0.79 or more.

Next, evaluation of constant supply capability for a shorter period oftime is illustrated.

In this evaluation of constant supply capability, first, a plurality ofcontrolled particles including brittle material fine particles with amean primary particle diameter in the submicron range were arranged, andmeasured for circularity. Then, by the following method, constant supplycapability of the controlled particles for each circularity wasevaluated.

To evaluate constant supply capability, a vibrating type supplyingapparatus was used. The supply rate was set to 0.5 g/min and 5 g/min,and the supply time was up to 3 minutes. For every 0.1 seconds at 0.5g/min and for every 1 second at 5 g/min, the flow rate was measured fromthe 0.1-second weight variation of the controlled particles suppliedfrom the vibrating type supplying apparatus. The mean value of this flowrate was calculated, and the standard deviation thereof was determined.

FIG. 7 is a graph for illustrating the relationship between meancircularity and supply quantity standard deviation in the case where thesupply rate is 0.5 g/min.

FIG. 8 is a graph for illustrating the relationship between meancircularity and supply quantity standard deviation in the case where thesupply rate is 5 g/min.

In FIGS. 7 and 8, the horizontal axis represents mean circularity, andthe vertical axis represents supply quantity standard deviation.

In this case, constant supply capability was determined as veryexcellent for a supply quantity standard deviation of 0.122 or less inFIG. 7 and 0.178 or less in FIG. 8.

Thus, as seen from FIGS. 7 and 8, if the mean circularity is 0.65 ormore, the supply quantity is stable. On the other hand, if the meancircularity is 0.59 or less, the supply quantity is unstable over time,impairing constant supply capability. Furthermore, also in the casewhere the supply rate exceeds 5 g/min, the stability of the supplyquantity exhibited the same tendency.

Furthermore, the D10 value of the controlled particle 31 can serve as anindicator in enhancing constant supply capability, aerosol concentrationuniformity and the like.

For example, if the D10 value is too small (if the particle diameter ofthe particle located at 10% from the smallest particle in the particlesize distribution of controlled particles is too small), adhesion andthe like are likely to occur, which interferes with smooth supply. Thismay impair constant supply capability, aerosol concentration uniformityand the like. Hence, the D10 value of the controlled particle 31 ispreferably above a prescribed value.

Here, the D10 value refers to a particle diameter of the particlelocated at 10% from the smallest particle (10% from the bottom) in theparticle size distribution of controlled particles. In determining theD10 value, a plurality of controlled particles are arbitrarily selected,and sorted in the ascending order of the circle-equivalent diameter, andthe particle diameter of the particle located nearest to 10% from thesmallest particle can be used as the D10 value. Here, the number ofcounts of controlled particles used for calculation is preferably 150 to200. The primary particle diameter of the brittle material fine particleis limited in the range from 0.1 to 5 μm, and depending on the primaryparticle diameter of the brittle material, aggregate particles andprimary particles which are not characterized as controlled particles,and groups of particles observed in the overlapping state of a pluralityof primary particles, are excluded. Specifically, in photographicdetermination, the group of data measured at a mean circle-equivalentdiameter of 5 μm or less is deleted. In the photographic determinationimage, the data of particles in contact with the outer peripheralboundary of the image, that is, the data of particles which are notcompletely captured in the image, are also deleted to ensure reliabilityin the value.

Furthermore, if the particle size distribution has a high frequency at30 μm or less, it is preferably treated similarly to the aforementionedcalculation of mean circle-equivalent diameter. In the case where theanalysis software (WinROOF manufactured by Mitani Corporation) is used,data for mean circle-equivalent diameter and D10 value can besimultaneously collected.

Here, the D10 value can be calculated by analyzing the opticalmicrograph or the like of the controlled particle 31 using commerciallyavailable shape analysis software. Such software illustratively includesanalysis software (WinROOF manufactured by Mitani Corporation)incorporated in a polarization optical microscope (LV-IMA manufacturedby Nikon Corporation).

In evaluating constant supply capability, first, controlled particlesincluding brittle material fine particles with a mean primary particlediameter of approximately 0.3 μm and being in the aforementioned rangeof mean compressive fracture strength were arranged, and sorted by D10values. Then, by the following method, constant supply capability of thecontrolled particles for each D10 value was evaluated.

To evaluate constant supply capability, a vibrating type supplyingapparatus was used. The supply rate was 5 g/min, the supply time was 30minutes, and the weight of controlled particles supplied from thevibrating type supplying apparatus was measured using an electronicbalance. The measurement resolution of the electronic balance was 0.01g. The temporal supply quantity was measured at every 5 seconds, andsupply quantity data from after 2 minutes to after 30 minutes were usedto determine the supply quantity and the standard deviation of thesupply quantity. Here, as a result of detailed observation on thesupplying state and the like, constant supply capability was determinedas good in the case where the supply quantity standard deviation was0.01 or less. Hence, the supply quantity standard deviation 0.01 wasadopted as a pass/fail criterion.

FIG. 9 is a graph for illustrating the relationship between D10 valueand supply quantity standard deviation. The horizontal axis representsD10 value, and the vertical axis represents supply quantity standarddeviation.

As seen from FIG. 9, if the D10 value is 6.6 μm or more, the supplyquantity standard deviation is 0.01 or less, exhibiting good constantsupply capability. On the other hand, if the D10 value is less than 6.6μm, the supply quantity is unstable over time, impairing constant supplycapability.

The foregoing relates to the lower bound of the D10 value. As seen fromFIG. 9, even if the D10 value increases, constant supply capability isnot impaired. Hence, the upper bound of the D10 value is notparticularly limited, but actually, equal to or less than the meancircle-equivalent diameter of the controlled particles. Hence, the D10value is 500 μm or less.

Thus, the D10 value is preferably 6.6 μm or more.

Furthermore, the particle size distribution deviation ratio of thecontrolled particle 31 can serve as an indicator in enhancing constantsupply capability, aerosol concentration uniformity and the like.

For example, if the particle size distribution deviation ratio is toolarge, that is, if the particle size distribution is too broad, smoothsupply is made difficult. This may impair constant supply capability,aerosol concentration uniformity and the like. Hence, the particle sizedistribution deviation ratio of the controlled particle 31 is preferablybelow a prescribed value.

The particle size distribution deviation ratio is calculated as(standard deviation σ of circle-equivalent diameter)/(meancircle-equivalent diameter). The particle size distribution deviationratio can be determined by arbitrarily selecting a plurality ofcontrolled particles, measuring their circle-equivalent diameters,determining the mean value and standard deviation a of thecircle-equivalent diameters, and calculating (standard deviation a ofcircle-equivalent diameter)/(mean circle-equivalent diameter). Here, thenumber of counts of controlled particles used for calculation ispreferably 150 to 200. The value of the particle size distributiondeviation ratio ranges from 0 to 1, and the value closer to 0 indicatesthat the controlled particles have a narrower particle size distributionand are more uniform in particle diameter.

The particle size distribution deviation ratio can be calculated byanalyzing the optical micrograph or the like of the controlled particle31 using commercially available shape analysis software. Such softwareillustratively includes analysis software (WinROOF manufactured byMitani Corporation) incorporated in a polarization optical microscope(LV-IMA manufactured by Nikon Corporation). In the calculation,aggregate particles and primary particles which are not characterized ascontrolled particles, and groups of particles observed in theoverlapping state of a plurality of primary particles, are excluded.Specifically, in photographic determination, the group of data measuredat a mean circle-equivalent diameter of 5 μm or less is deleted. In thephotographic determination image, the data of particles in contact withthe outer peripheral boundary of the image, that is, the data ofparticles which are not completely captured in the image, are alsodeleted to ensure reliability in the value.

Furthermore, if the particle size distribution has a high frequency at30 μm or less, it is preferably treated similarly to the aforementionedcalculation of mean circle-equivalent diameter.

In evaluating constant supply capability, first, controlled particlesincluding brittle material fine particles with a mean primary particlediameter of approximately 0.3 μm and being in the aforementioned rangeof mean compressive fracture strength were arranged, and sorted byparticle size distribution deviation ratios. Then, by the followingmethod, constant supply capability of controlled particles for eachparticle size distribution deviation ratio was evaluated.

To evaluate constant supply capability, a vibrating type supplyingapparatus was used. The supply rate was 5 g/min, the supply time was 30minutes, and the weight of controlled particles supplied from thevibrating type supplying apparatus was measured using an electronicbalance. The measurement resolution of the electronic balance was 0.01g. The temporal supply quantity was measured at every 5 seconds, andsupply quantity data from after 2 minutes to after 30 minutes were usedto determine the supply quantity and the standard deviation of thesupply quantity. Here, as a result of detailed observation on thesupplying state and the like, constant supply capability was determinedas good in the case where the supply quantity standard deviation was0.01 or less. Hence, the supply quantity standard deviation 0.01 wasadopted as a pass/fail criterion.

FIG. 10 is a graph for illustrating the relationship between particlesize distribution deviation ratio and supply quantity standarddeviation. The horizontal axis represents particle size distributiondeviation ratio, and the vertical axis represents supply quantitystandard deviation.

As seen from FIG. 10, if the particle size distribution deviation ratiois 0.59 or less, the supply quantity standard deviation is 0.01 or less,exhibiting good constant supply capability. On the other hand, if theparticle size distribution deviation ratio exceeds 0.59, the supplyquantity is unstable over time, impairing constant supply capability.

The foregoing relates to the upper bound of the particle sizedistribution deviation ratio. As seen from FIG. 10, even if the particlesize distribution deviation ratio decreases, constant supply capabilityis not impaired. Hence, the lower bound of the particle sizedistribution deviation ratio is not particularly limited.

Thus, the particle size distribution deviation ratio is preferably 0.59or less.

Furthermore, the angle of repose of the controlled particle 31 can serveas an indicator in enhancing constant supply capability, aerosolconcentration uniformity and the like.

For example, if the angle of repose is too large, that is, if flow isless likely to occur, smooth supply is made difficult. This may impairconstant supply capability, aerosol concentration uniformity and thelike. Hence, the angle of repose of the controlled particle 31 ispreferably below a prescribed value.

The angle of repose was determined as follows. First, controlledparticles are dropped in small quantities with a rate of 5 g/min or lesstoward the center of a disk having a diameter of 30 mm, and piled upuntil the controlled particles begin to spill from the disk. Then, forexample, a photograph was taken sideways. By image analysis, in thephotograph of the conical pile of controlled particles, the anglesbetween the bottom side and the left and right slope were measured, andthe mean value of the angles was calculated to determine the angle ofrepose.

In evaluating constant supply capability, first, controlled particlesincluding brittle material fine particles with a mean primary particlediameter of approximately 0.3 μm and being in the aforementioned rangeof mean compressive fracture strength were arranged, and sorted byangles of repose. Then, by the following method, constant supplycapability of the controlled particles for each angle of repose wasevaluated.

To evaluate constant supply capability, a vibrating type supplyingapparatus was used. The supply rate was 5 g/min, the supply time was 30minutes, and the weight of controlled particles supplied from thevibrating type supplying apparatus was measured using an electronicbalance. The measurement resolution of the electronic balance was 0.01g. The temporal supply quantity was measured at every 5 seconds, andsupply quantity data from after 2 minutes to after 30 minutes were usedto determine the supply quantity and the standard deviation of thesupply quantity. Here, as a result of detailed observation on thesupplying state and the like, constant supply capability was determinedas good in the case where the supply quantity standard deviation was0.01 or less. Hence, the supply quantity standard deviation 0.01 wasadopted as a pass/fail criterion.

FIG. 11 is a graph for illustrating the relationship between angle ofrepose and supply quantity standard deviation. The horizontal axisrepresents angle of repose, and the vertical axis represents supplyquantity standard deviation.

As seen from FIG. 11, if the angle of repose is 42.5 degrees or less,the supply quantity standard deviation is 0.01 or less, exhibiting goodconstant supply capability. On the other hand, if the angle of reposeexceeds 42.5 degrees, the supply quantity is unstable over time, whichmay impair constant supply capability.

The foregoing relates to the upper bound of the angle of repose. As alsoseen from FIG. 11, even if the angle of repose decreases, constantsupply capability is not impaired. Hence, the lower bound of the angleof repose is not particularly limited. That is, the angle of repose onlyneeds to exceed 0 degrees.

Thus, the angle of repose is preferably 42.5 degrees or less.

Next, evaluation of constant supply capability for a shorter period oftime is illustrated.

In this evaluation of constant supply capability, first, a plurality ofcontrolled particles including brittle material fine particles with amean primary particle diameter in the submicron range were arranged, andmeasured for angle of repose. Then, by the following method, constantsupply capability of the controlled particles for each angle of reposewas evaluated.

To evaluate constant supply capability, a vibrating type supplyingapparatus was used. The supply rate was set to 0.5 g/min and 5 g/min,and the supply time was up to 3 minutes. For every 0.1 seconds at 0.5g/min and for every 1 second at 5 g/min, the flow rate was measured fromthe 0.1-second weight variation of the controlled particles suppliedfrom the vibrating type supplying apparatus. The mean value of this flowrate was calculated, and the standard deviation thereof was determined.

FIG. 12 is a graph for illustrating the relationship between angle ofrepose and supply quantity standard deviation in the case where thesupply rate is 0.5 g/min.

FIG. 13 is a graph for illustrating the relationship between angle ofrepose and supply quantity standard deviation in the case where thesupply rate is 5 g/min.

In FIGS. 12 and 13, the horizontal axis represents angle of repose, andthe vertical axis represents supply quantity standard deviation.

In this case, constant supply capability was determined as excellent fora supply quantity standard deviation of 0.192 or less in FIG. 12 and1.018 or less in FIG. 13. Furthermore, constant supply capability wasdetermined as very excellent for a supply quantity standard deviation of0.122 or less in FIG. 12 and 0.178 or less in FIG. 13.

Thus, as seen from FIGS. 12 and 13, if the angle of repose is 48° orless, a high constant supply capability is achieved. Furthermore, if theangle of repose is 44° or less, the supply quantity standard deviationis especially small, and hence the constant supply capability is moreexcellent. On the other hand, if the angle of repose exceeds 48°, thesupply quantity is unstable over time, impairing constant supplycapability. Furthermore, also in the case where the supply rate exceedsg/min, the stability of the supply quantity exhibited the same tendency.

Furthermore, in the case of using controlled particles having an angleof repose of 48° or less, the quantity of brittle material fineparticles sprayed from the nozzle was stabilized.

Thus, controlled particles having an angle of repose of 48° or less canbe suitably used also in the case of forming a large-area film-likestructure in which accuracy in the thickness of the structure formed isrelatively unnecessary. Furthermore, they can be suitably used also inthe case of forming a composite structure which is to be polished in asubsequent process. Furthermore, they can be suitably used also in thecase of reciprocation by repeating relative movement between the nozzleand the substrate to gain the thickness of the structure formed and toaverage the thickness.

Furthermore, controlled particles having an angle of repose of 44° orless are very excellent in the stability of the quantity of brittlematerial fine particles sprayed from the nozzle.

Thus, this embodiment can exhibit high manufacturing performance also inthe case of forming a structure requiring high accuracy in thickness andin the case of forming a thin film-like structure having a thickness ofseveral μm or less. By using controlled particles having an angle ofrepose of 44° or less in such applications, more favorable structurescan be formed.

To favorably form a composite structure, the quantity of water in thecontrolled particle is preferably taken into consideration. On the basisof the inventors' findings, if the quantity of wafer in the controlledparticle 31 is 0.45 weight % or less, composite structure formation canbe favorably performed. The quantity of wafer can be determinedillustratively by measuring the weight decrease of controlled particles31 when heated to approximately 300° C.

Furthermore, from the viewpoint of preventing contamination of thecomposite structure formed, the carbon content in the controlledparticle 31 is preferably 1 weight % or less. A resin binder may be usedin producing controlled particles 31. In the case of composite structureformation using the aerosol deposition method for film formation atnormal temperature, if the resin binder is mixed in the controlledparticles 31, it may interfere with aerosolation, or cause the troubleof contaminating the composite structure with the resin. Hence, thecontrolled particles including the resin binder need to be heat treatedat several hundred degrees to burn off the resin binder. In this case,insufficient heat treatment may leave carbon in the controlled particlesand allow impurity (carbon) to be mixed in the composite structureformed. Hence, preferably, depending on the kind of the resin binder,for example, the heat treatment temperature is suitably selected tominimize the quantity of residual carbon. On the basis of the inventors'findings, if the carbon content is 1 weight % or less, compositestructure formation can be favorably performed, and the effect ofimpurity, if any, mixed in the composite structure can be prevented.

The controlled particle 31 as described above can be manufactured byusing a spray dryer method, pan granulator, pot granulator and the like.Here, as described above, in manufacturing the controlled particle 31, abinder may be added, or water and the like may be added. The spray dryermethod, pan granulator, pot granulator and the like can be based onknown techniques, and hence the description thereof is omitted. Theshape, size, and hardness of the controlled particle can be varied bysuitably setting various control factors in these methods, such as thespray quantity, spray condition, temperature and the like of the spraydryer, common factors of the granulator, including rotation speed androtation time, as well as the structure and size of the granulator, andthe quantity of water added thereto.

FIG. 14 is a schematic view for illustrating the basic configuration ofa composite structure formation system according to a second embodimentof the invention. More specifically, FIG. 14A is a block diagram forillustrating the basic configuration of a composite structure formationsystem (aerosol deposition apparatus), FIG. 14B schematically shows theprocess flow from storage to aerosolation of controlled particles, andFIG. 14C shows state changes in the process from storage to aerosolationof controlled particles. Here, FIGS. 14B and 14C are depicted so as tocorrespond to the components shown in FIG. 14A.

As shown in FIG. 14A, the composite structure formation system (aerosoldeposition apparatus) 100 a according to this embodiment includes astorage mechanism 1, a constant supply mechanism 2, a gas supplymechanism 3, an aerosolation mechanism 4, and a discharge port 5, likethe composite structure formation system 100 illustrated in FIG. 1A.

In addition, this embodiment further includes a solid-gas mixed phaseflow formation mechanism 6 between the constant supply mechanism 2 andthe aerosolation mechanism 4.

The solid-gas mixed phase flow formation mechanism 6 is intended to forma solid-gas mixed phase flow 33 from controlled particles 31 supplied bythe constant supply mechanism 2 and a gas G supplied by the gas supplymechanism 3. The solid-gas mixed phase flow 33 formed by the solid-gasmixed phase flow formation mechanism 6 is supplied to the aerosolationmechanism 4 through a supply channel 16.

The solid-gas mixed phase flow formation mechanism 6 thus providedserves to form a homogeneous and stable solid-gas mixed phase flow 33.Furthermore, the solid-gas mixed phase flow 33 thus formed serves notonly to supply controlled particles 31, but also to accelerate thecontrolled particles 31 toward the aerosolation mechanism 4. Hence,disaggregation by mechanical impact using the kinetic energy of theaccelerated controlled particles 31 facilitates aerosolation.

The rest of the configuration and the associated operations are the sameas those described with reference to FIG. 1, and hence the descriptionthereof is omitted.

FIG. 15 is a schematic view for illustrating the basic configuration ofa composite structure formation system according to a third embodimentof the invention. More specifically, FIG. 15A is a block diagram forillustrating the basic configuration of a composite structure formationsystem (aerosol deposition apparatus), FIG. 15B schematically shows theprocess flow from storage to aerosolation of controlled particles, andFIG. 15C shows state changes in the process from storage to aerosolationof controlled particles. Here, FIGS. 15B and 15C are depicted so as tocorrespond to the components shown in FIG. 15A.

As shown in FIG. 15A, the composite structure formation system (aerosoldeposition apparatus) 100 b according to this embodiment includes astorage mechanism 1, a constant supply mechanism 2, a gas supplymechanism 3, an aerosolation mechanism 4, and a discharge port 5.

In this embodiment, controlled particles 31 are supplied from theconstant supply mechanism 2 to the aerosolation mechanism 4 withoutforming the aforementioned solid-gas mixed phase flow 33.

Furthermore, the aerosolation mechanism 4 is supplied with a gas G fromthe gas supply mechanism 3. In the aerosolation mechanism 4, thecontrolled particles 31 supplied are disaggregated to form an aerosol 32in which fine particles 30P are dispersed in the gas G.

Disaggregation of the controlled particle 31 can be performedillustratively by providing a “grinding mechanism”, not shown, in theaerosolation mechanism 4 to grind the supplied controlled particles 31.

Alternatively, the supplied controlled particles 31 can be acceleratedby electrostatic attraction or gravity and disaggregated by mechanicalimpact based on the kinetic energy of the accelerated controlledparticles 31.

The rest of the configuration and the associated operations are the sameas those described with reference to FIG. 1, and hence the descriptionthereof is omitted.

FIG. 16 is a schematic view for illustrating a first example of thecomposite structure formation system (aerosol deposition apparatus)according to the embodiment of the invention.

The same components as those described with reference to FIG. 1 arelabeled with like reference numerals, and the description thereof isomitted.

This example includes a structure formation chamber 8. The dischargeport 5, in at least its tip portion, and a support scan mechanism 10 forsupporting a substrate 7 are placed in the structure formation chamber8. The substrate 7 transported into the structure formation chamber 8 issupported by, for example, an electrostatic chuck incorporated in thesupport scan mechanism 10.

The internal space of the structure formation chamber 8 can bemaintained in a reduced-pressure state by an evacuation mechanism 9. Theevacuation mechanism 9 can illustratively be a rotary pump, and canmaintain a reduced-pressure atmosphere, which has a lower pressure thanthe atmospheric pressure, inside the structure formation chamber 8.

The aerosol generated in the aerosolation mechanism 4 is sprayed fromthe discharge port 5 toward the substrate 7, and a film-like structure26 made of raw material fine particles is formed on the substrate 7.Here, because of the reduced-pressure environment in the structureformation chamber 8, the aerosol is accelerated by the pressuredifference and collides with the substrate 7. Consequently, a robustfilm-like structure can be formed on the substrate 7 as described above.

Furthermore, by maintaining the structure formation chamber 8 in areduced-pressure state, the “new surface” formed by collision of theaerosol with the substrate 7 can be maintained in an active state for alonger period of time, which serves to increase the compactness andstrength of the film-like structure.

Furthermore, a film-like structure 26 can be formed while the substrate7 is supported on the support scan mechanism 10 to suitably move itsposition in at least one of XYZθ directions. That is, by spraying theaerosol while suitably scanning the substrate 7 by the support scanmechanism 10, a film-like structure 26 can be formed on a substrate 7having a larger area than the beam size of the aerosol sprayed from thedischarge port 5.

According to this example, the aforementioned controlled particles 31are stored in the storage mechanism 1, and reliably supplied by theconstant supply mechanism 2. Thus, the supply quantity can be readilymade constant. Furthermore, as described above, disaggregation in theprocess of supply to the aerosolation mechanism 4 and adhesion, stackingand the like associated therewith can be prevented, and hence constantsupply capability can be significantly enhanced. Thus, the fine particleconcentration in the aerosol can be made constant. Consequently, in thecase where the discharge port 5 and the substrate 7 are relativelyscanned to form a film-like structure 26 on the surface of a large-areasubstrate 7, the fine particle concentration in the aerosol can be keptconstant. Hence, the film thickness and film quality can be made uniformacross a large area.

FIG. 17 is a schematic view for illustrating a second example of thecomposite structure formation system (aerosol deposition apparatus)according to the embodiment of the invention.

The same components as those described with reference to FIGS. 14 and 16are labeled with like reference numerals, and the description thereof isomitted.

In this example, controlled particles 31 stored inside the storagemechanism 1 are supplied to the solid-gas mixed phase flow formationmechanism 6 by the constant supply mechanism 2. Then, in the solid-gasmixed phase flow formation mechanism 6, a solid-gas mixed phase flow isformed from the controlled particles 31 supplied by the constant supplymechanism 2 and the gas supplied by the gas supply mechanism 3. Thesolid-gas mixed phase flow formed is supplied to the aerosolationmechanism 4 through a supply channel 16.

In addition, this example further includes a discharge port 11 having anaccelerating means and a flow regulating means, and a support scanmechanism 12 is connected to the discharge port 11. The aerosolgenerated in the aerosolation mechanism 4 is passed through a duct 13and sprayed from the discharge port 11 toward the substrate 7 a. Theaerosol can be accelerated by using the accelerating means of thedischarge port 11 as well as the jet stream, compression effect and thelike achieved by providing a difference in the flow channel diameter.

In this example, the discharge port 11 is supported by the support scanmechanism 12 and allowed to move in at least one of XYZθ directions.Depending on the cases, such as the substrate 7 a has a solid structureor the locations to form a film-like structure 26 a are scattered, theaerosol is sprayed while the discharge port 11 is moved with the lineardistance between the discharge port 11 and the substrate 7 a surfacebeing kept, and thus a film-like structure 26 a being uniform across alarge area can be formed on the substrate 7 a. Here, if the duct 13 isflexible, the displacement due to the movement of the discharge port 11can be absorbed. Examples of the flexible duct 13 include a duct made ofan elastic material such as rubber and a duct such as a bellows. Inaddition, the discharge port 11 and the substrate 7 a only need to moverelatively, and the support scan mechanism 10 may be allowed to move inat least one of XYZθ directions.

Also in this example, the aforementioned controlled particles 31 arestored in the storage mechanism 1, and reliably supplied by the constantsupply mechanism 2. Thus, the supply quantity can be readily madeconstant. Furthermore, as described above, disaggregation in the processof supply to the aerosolation mechanism 4 and adhesion, stacking and thelike associated therewith can be prevented, and hence constant supplycapability can be significantly enhanced. Thus, the fine particleconcentration in the aerosol can be made constant. Consequently, also inthe case where the discharge port 11 and the substrate 7 a arerelatively scanned to form a film-like structure 26 a on the surface ofthe substrate 7 a having a solid structure or at scattered locations onthe surface of the substrate 7 a, the fine particle concentration in theaerosol can be kept constant. Hence, the film thickness and film qualitycan be made uniform across a large area.

FIG. 18 is a schematic view for illustrating a third example of thecomposite structure formation system (aerosol deposition apparatus)according to the embodiment of the invention.

The same components as those described with reference to FIGS. 1, 16 andthe like are labeled with like reference numerals, and the descriptionthereof is omitted.

In this example, a measuring mechanism 14 for measuring the fineparticle concentration in the aerosol is provided between the dischargeport 5 and the substrate 7. The measuring mechanism 14 is electricallyconnected to a control mechanism 15. The control mechanism 15 iselectrically connected also to the constant supply mechanism 2, the gassupply mechanism 3, and the evacuation mechanism 9 for the feedbackcontrol described later. In the connection for the feedback controldescribed later, it is only necessary to provide electrical connectionto at least the constant supply mechanism 2.

The measuring mechanism 14 can be provided at a location where theconcentration of fine particles contained in the aerosol can bemeasured. Here, for example, as shown in FIG. 18, the measuringmechanism 14 may be provided outside or inside the structure formationchamber 8, or inside and outside the structure formation chamber 8. Thenumber of measuring mechanisms 14 provided can also be suitably varied.

In this example, the concentration of fine particles contained in theaerosol sprayed from the discharge port 5 is measured by the measuringmechanism 14, and the measured information is transmitted from themeasuring mechanism 14 to the control mechanism 15. On the basis of thetransmitted information, the control mechanism 15 performs feedbackcontrol on the constant supply mechanism 2, the gas supply mechanism 3,and the evacuation mechanism 9. Here, it is only necessary to performfeedback control on at least the constant supply mechanism 2.

FIGS. 19 to 21 are schematic views for illustrating measuring mechanismswhich can be used in this embodiment.

As shown in FIG. 19, the measuring mechanism 14 can illustrativelyinclude a light projection means 1402 such as a laser and a lightreceiving means 1404 for monitoring the light. In this case, theconcentration of fine particles contained in the aerosol can be measuredby irradiating the aerosol with laser light from the light projectionmeans 1402 and monitoring the quantity of transmission thereof.

Alternatively, as illustrated in FIG. 20, the aerosol may be irradiatedwith laser light from the light projection means 1402 such as a laser,and the reflected light may be monitored by the light receiving means1404 a such as a CCD (charge coupled device) sensor.

Alternatively, as illustrated in FIG. 21, the constant supply mechanism2 can be provided with a load cell to measure the weight change of theconstant supply mechanism 2, thereby measuring the supply quantity. Byvarying the amplitude and the like of a vibrator in accordance with theweight change, controlled particles 31 can be always supplied in aconstant weight. In this case, for higher readability of the weightchange, a multi-stage constant supply mechanism can be used to measureand control the supply quantity with higher precision.

Also in this example, the aforementioned controlled particles 31 arestored in the storage mechanism 1, and reliably supplied by the constantsupply mechanism 2. Thus, the supply quantity can be readily madeconstant. Furthermore, as described above, disaggregation in the processof supply to the aerosolation mechanism 4 and adhesion, stacking and thelike associated therewith can be prevented, and hence constant supplycapability can be significantly enhanced. Thus, the fine particleconcentration in the aerosol can be made constant.

Furthermore, the measuring mechanism 14 is provided, and feedbackcontrol is performed on at least the constant supply mechanism 2 by thecontrol mechanism 15. Thus, even if any fluctuation or temporalvariation occurs in the concentration of fine particles contained in thesprayed aerosol, the concentration of fine particles contained in theaerosol can be accurately controlled. Consequently, the fine particleconcentration in the aerosol can be kept constant. Hence, the filmthickness and film quality can be made uniform across a large area.

Because the controlled particles used are excellent in suppliability andready to be supplied in constant quantities, the aforementioned feedbackcontrol is highly accurate, and favorable.

Next, examples of the constant supply mechanism 2 are illustrated.

FIG. 22 is a schematic view for illustrating a first example of theconstant supply mechanism 2.

More specifically, FIG. 22 is a schematic perspective view of a relevantpart of the constant supply mechanism 2.

In this example, an opening is provided at the vertical bottom of thestorage mechanism 1 storing controlled particles 31, and a roller 210 isprovided so as to occlude this opening. The roller 210 has a pluralityof recesses 212 on its surface, and rotates in the direction of thearrow A or in the direction opposite thereto. The recess 212 has acapacity sufficiently larger than the controlled particle 31. The gapbetween the inner sidewall of the storage mechanism 1 and the surface ofthe roller 210 is sufficiently narrowed as long as the rotation of theroller 210 is not hampered, so that controlled particles 31 do not dropout of this gap. Here, an elastic seal such as rubber may be provided onthe inner sidewall or opening end of the storage mechanism 1 so as to bein contact with the surface of the roller 210.

In the storage mechanism 1, controlled particles 31 are filled by theirself-weight in the recess 212 of the roller 210, and supplied to theoutside (downside) of the storage mechanism 1 by the rotation of theroller 210. When the recess 212 is directed vertically downward, thecontrolled particles 31 fall by self-weight. By providing the solid-gasmixed phase flow formation mechanism 6 or the aerosolation mechanism 4at this falling destination, an aerosol having a constant concentrationof fine particles can be formed.

In this example, a prescribed quantity of controlled particles 31 filledin the recess 212 are supplied from the storage mechanism 1 in responseto the rotation of the roller 210 and falls toward the solid-gas mixedphase flow formation mechanism 6 or the aerosolation mechanism 4. Thatis, a prescribed quantity of controlled particles 31 can be successivelysupplied.

Furthermore, in the storage mechanism 1, the controlled particles 31 arefilled by their self-weight in the recess 212 of the roller 210, andhence not excessively packed down. That is, the controlled particles 31are supplied without collapse. Thus, it is possible to preventcontrolled particles 31 with altered properties from being supplied fromthe constant supply mechanism 2.

Furthermore, because the controlled particles 31 are not excessivelypacked down into the recess 212, the controlled particles 31 therein cansmoothly fall by self-weight when the recess 212 is directed verticallydownward by the rotation of the roller 210. That is, it is also possibleto avoid the problem of the controlled particles 31 failing to fall frominside the recess 212, and the controlled particles 31 can be stablysupplied. Hence, the controlled particles 31 with the aforementionedproperties such as mean compressive fracture strength, circularity, andangle of repose being adjusted can be directly supplied, therebystabilizing the supply. Thus, stable supply on target can be achievedwithout stacking.

FIG. 23 is a schematic view for illustrating a second example of theconstant supply mechanism 2.

Also in this example, an opening is provided at the vertical bottom ofthe storage mechanism 1 storing controlled particles 31. Furthermore, aroller 222 is provided so as to occlude this opening. The roller 222 hasa plurality of protrusions 224 on its surface, and rotates in thedirection of the arrow A or in the direction opposite thereto.

In this example, because the protrusions 224 are provided on the surfaceof the roller 222, a gap corresponding to the height of the protrusion224 occurs between the surface of the roller 222 and the inner sidewallof the storage mechanism 1. However, by providing the protrusions 224relatively densely on the surface of the roller 222 or suitablyadjusting the shape and layout of the protrusions 224, controlledparticles 31 can be prevented from continuously dropping out of the gapbetween the opening at the lower end of the storage mechanism 1 and thesurface of the roller 222.

In response to the rotation of the roller 222, controlled particles 31stored in the storage mechanism 1 are pushed out by the protrusions 224,fall by self-weight, and are supplied to the solid-gas mixed phase flowformation mechanism 6 or the aerosolation mechanism 4. The controlledparticles 31 stored in the storage mechanism 1 are ejected as if theyare scraped out by each protrusion 224. Hence, the quantity ofcontrolled particles 31 can be controlled by the shape and number of theprotrusions 224, and the rotation speed.

In this example, in the storage mechanism 1, the controlled particles 31are in contact with the surface of the roller 222 by their self-weight,and pushed out by the protrusions 224. Hence, the controlled particles31 are not excessively packed down. That is, the controlled particles 31are supplied without collapse. Thus, it is possible to preventcontrolled particles 31 with altered properties from being supplied fromthe constant supply mechanism 2. Hence, the controlled particles 31 withthe aforementioned properties such as mean compressive fracturestrength, circularity, and angle of repose being adjusted can bedirectly supplied, thereby stabilizing the supply. Thus, stable supplyon target can be achieved without stacking.

FIG. 24 is a schematic view for illustrating a third example of theconstant supply mechanism 2.

In this example, a generally circular opening is provided at thevertical bottom of the storage mechanism 1 storing controlled particles31. Furthermore, a mesh 230 is provided at this opening. The mesh 230rotates in the direction of the arrow A or in the direction oppositethereto while being in contact with the bottom of the storage mechanism1.

In this example, by the rotation of the mesh 230, controlled particles31 fall through the openings of the mesh 230. The falling quantity ofcontrolled particles 31 depends on the opening size, rotation speed andthe like of the mesh 230. Here, if the opening size of the mesh is inthe range from 2 to 7 times the mean particle diameter of the controlledparticles 31, the controlled particles 31 can be bridged over each otherwhen the mesh 230 is at rest, and hence unnecessary fall can be avoided.Consequently, the supply quantity of controlled particles 31 can bereadily controlled by the rotation of the mesh 230.

In this example, in the storage mechanism 1, the controlled particles 31are in contact with the surface of the mesh 230 by their self-weight,and fall outside through the openings. Hence, the controlled particles31 are not excessively packed down. That is, the controlled particles 31are supplied without collapse. Thus, it is possible to preventcontrolled particles 31 with altered properties from being supplied fromthe constant supply mechanism 2. Hence, the controlled particles 31 withthe aforementioned properties such as mean compressive fracturestrength, circularity, and angle of repose being adjusted can bedirectly supplied, thereby stabilizing the supply. Thus, stable supplyon target can be achieved without stacking.

Furthermore, a plurality of controlled particles 31 are supplied nearlysimultaneously and continuously through a plurality of openings of themesh 230. That is, numerous controlled particles 31 are always suppliedcontinuously to the solid-gas mixed phase flow formation mechanism 6 orthe aerosolation mechanism 4, and the supply quantity of the controlledparticles 31 is averaged in terms of time. Thus, a constant quantity ofcontrolled particles 31 is always stably supplied, and hence an aerosolhaving a constant fine particle concentration can be stably generated.

FIG. 25 is a schematic view for illustrating a fourth example of theconstant supply mechanism 2.

Also in this example, like that described above with reference to thethird example, a circular opening is provided at the vertical bottom ofthe storage mechanism 1 storing controlled particles 31. Furthermore, amesh 230 is provided at this opening. A brush 232 is placed on the mesh230, and rotates in the direction of the arrow A or in the directionopposite thereto while being in contact with the mesh 230. Furthermore,a vibrator 234 is attached to the storage mechanism 1. The vibrator 234vibrates the wall surface and the like of the storage mechanism 1,serving to smoothly drop and supply the controlled particles 31 storedin the storage mechanism 1 toward the brush 232 and the mesh 230.Furthermore, by applying vibration to the controlled particles 31 in thestorage mechanism 1, the effect of enhancing their fluidity is alsoachieved.

Also in the first to third example, the vibrator 234 can be providedlikewise to achieve the same operation and effect.

In this example, in response to the rotation of the brush 232,controlled particles 31 fall through the openings of the mesh 230. Thefalling quantity of controlled particles 31 depends on the opening sizeof the mesh 230 and the bristle density and rotation speed of the brush232. Here, if the opening size of the mesh is in the range from 2 to 7times the mean particle diameter of the controlled particles 31, thecontrolled particles 31 can be bridged over each other when the mesh 230is at rest, and hence unnecessary fall can be avoided. Consequently, thesupply quantity of controlled particles 31 can be readily controlled bythe rotation of the brush 232.

In response to the motion of each bristle tip of the brush 232 passingthrough the opening of the mesh 230, controlled particles 31 are pushedout of the opening. Microscopically, the controlled particles 31 arelightly pushed out of the mesh, dropped, and supplied to the solid-gasmixed phase flow formation mechanism 6 or the aerosolation mechanism 4.That is, the controlled particles 31 are supplied without collapse.Thus, it is possible to prevent controlled particles 31 with alteredproperties from being supplied from the constant supply mechanism 2.Hence, the controlled particles 31 with the aforementioned propertiessuch as mean compressive fracture strength, circularity, and angle ofrepose being adjusted can be directly supplied, thereby stabilizing thesupply. Thus, stable supply on target can be achieved without stacking.

Furthermore, a plurality of controlled particles 31 are supplied nearlysimultaneously and continuously through a plurality of openings of themesh 230. That is, in the aerosolation mechanism 4, numerous controlledparticles 31 are always supplied continuously, and the supply quantityof the controlled particles 31 is averaged in terms of time. Thus, aconstant quantity of controlled particles 31 is always stably supplied,and hence an aerosol having a constant fine particle concentration canbe stably generated.

FIG. 26 is a schematic view for illustrating a fifth example of theconstant supply mechanism 2.

In this example, a supply channel 235 is provided below the storagemechanism 1 storing controlled particles 31, and a vibrator 234 isplaced on the supply channel 235. The controlled particles 31 stored inthe storage mechanism 1 pass through an orifice, not shown, and aprescribed quantity thereof is supplied to the supply channel 235. Thecontrolled particles 31 supplied to the supply channel 235 are suppliedfrom the supply channel 235 by vibration of the vibrator 234.

In this example, in the storage mechanism 1, the controlled particles 31are passed through the orifice, not shown, by their self-weight anddropped outside (to the supply channel 235). Hence, the controlledparticles 31 are not excessively packed down. Likewise, the controlledparticles 31 supplied to the supply channel 235 are dropped outside byvibration of the vibrator 234, and hence the properties of thecontrolled particles 31 do not change. That is, the controlled particles31 are supplied from the constant supply mechanism 2 to the outsidewithout change in their properties. Hence, the controlled particles 31with the aforementioned properties such as mean compressive fracturestrength, circularity, and angle of repose being adjusted can bedirectly supplied, thereby stabilizing the supply. Thus, stable supplyon target can be achieved without stacking.

Furthermore, a plurality of controlled particles 31 are supplied nearlysimultaneously and continuously. That is, in the aerosolation mechanism4, numerous controlled particles 31 are always supplied continuously,and the supply quantity of the controlled particles 31 is averaged interms of time. Thus, a constant quantity of controlled particles 31 isalways stably supplied, and hence an aerosol having a constant fineparticle concentration can be stably generated.

FIG. 27 is a schematic view for illustrating a sixth example of theconstant supply mechanism 2.

In this example, a turntable provided with grooves is placed below thestorage mechanism 1 storing controlled particles 31, and a scraper isplaced on the rotation path of the turntable.

The controlled particles 31 introduced into the groove of the turntableare supplied from the storage mechanism 1 by the rotation of theturntable. Then, the controlled particles 31 introduced into the grooveare scraped out by the scraper.

In this example, in the storage mechanism 1, the controlled particles 31are in contact with the surface of the turntable by their self-weight,introduced into the grooves, and then scraped out by the scraper. Hence,the controlled particles 31 are not excessively packed down. That is,the controlled particles 31 are supplied without collapse. Thus, it ispossible to prevent controlled particles 31 with altered properties frombeing supplied from the constant supply mechanism 2. Hence, thecontrolled particles 31 with the aforementioned properties such as meancompressive fracture strength, circularity, and angle of repose beingadjusted can be directly supplied, thereby stabilizing the supply. Thus,stable supply on target can be achieved without stacking.

Furthermore, a plurality of controlled particles 31 are supplied nearlysimultaneously and continuously through a plurality of grooves of theturntable. That is, in the aerosolation mechanism 4, numerous controlledparticles 31 are always supplied continuously, and the supply quantityof the controlled particles 31 is averaged in terms of time. Thus, inthe aerosolation mechanism 4, a constant quantity of controlledparticles 31 is always stably supplied, and hence an aerosol having aconstant fine particle concentration can be stably generated.

FIG. 28 is a schematic view for illustrating a seventh example of theconstant supply mechanism 2.

In this example, a screw is provided below the storage mechanism 1storing controlled particles 31, and a motor, not shown, for rotatingthe screw is provided at the end of the screw. Furthermore, to smoothlyrotate the screw, an outer wall having a certain length is provided onthe screw, and both ends of the outer wall are opened. The controlledparticles 31 introduced into the groove of the screw are supplied fromthe storage mechanism 1 by the rotation of the screw. At this time, thecontrolled particles 31 are leveled off to a constant quantity by theclearance with the outer wall, moved therethrough, and dropped from theend of the outer wall at a constant rate.

In this example, in the storage mechanism 1, the controlled particles 31are in contact with the surface of the screw by their self-weight.Hence, the controlled particles 31 are not excessively packed down. Thatis, the controlled particles 31 are supplied without collapse. Thus, itis possible to prevent controlled particles 31 with altered propertiesfrom being supplied from the constant supply mechanism 2. Hence, thecontrolled particles 31 with the aforementioned properties such as meancompressive fracture strength, circularity, and angle of repose beingadjusted can be directly supplied, thereby stabilizing the supply. Thus,stable supply on target can be achieved without stacking.

Furthermore, a plurality of controlled particles 31 are supplied nearlysimultaneously and continuously by the screw. That is, in theaerosolation mechanism 4, numerous controlled particles 31 are alwayssupplied continuously, and the supply quantity of the controlledparticles 31 is averaged in terms of time. Thus, in the aerosolationmechanism 4, a constant quantity of controlled particles 31 is alwaysstably supplied, and hence an aerosol having a constant fine particleconcentration can be stably generated.

FIG. 29 is a schematic view for illustrating an eighth example of theconstant supply mechanism 2.

In this example, an orifice 237 is provided at the bottom of the storagemechanism 1 storing controlled particles 31, and a belt conveyor 236 isplaced therebelow nearly horizontally with respect to the ground.

The controlled particles 31 leveled off by the orifice 237 are suppliedon top of the belt conveyor 236. The belt conveyor 236 is driven at aconstant speed. Hence, after being moved a prescribed length, thecontrolled particles 31 are dropped from the end of the belt conveyor236 at a constant rate.

In this example, in the storage mechanism 1, the controlled particles 31pass through the orifice 237 and fall on the belt conveyor 236 by theirself-weight. Hence, the controlled particles 31 are not excessivelypacked down. That is, the controlled particles 31 are supplied withoutcollapse. Thus, it is possible to prevent controlled particles 31 withaltered properties from being supplied from the constant supplymechanism 2. Hence, the controlled particles 31 with the aforementionedproperties such as mean compressive fracture strength, circularity, andangle of repose being adjusted can be directly supplied, therebystabilizing the supply. Thus, stable supply on target can be achievedwithout stacking.

Furthermore, a plurality of controlled particles 31 are supplied nearlysimultaneously and continuously through the belt conveyor 236. That is,in the aerosolation mechanism 4, numerous controlled particles 31 arealways supplied continuously, and the supply quantity of the controlledparticles 31 is averaged in terms of time. Thus, in the aerosolationmechanism 4, a constant quantity of controlled particles 31 is alwaysstably supplied, and hence an aerosol having a constant fine particleconcentration can be stably generated.

FIG. 30 is a schematic view for illustrating a ninth example of theconstant supply mechanism 2.

In this example, an orifice 238 is provided at the bottom of the storagemechanism 1 storing controlled particles 31, and a shutter 239 foropening and closing the orifice 238 is further provided. The openingshape of the orifice 238 is suitably determined in accordance with thesize of the controlled particle 31. By opening and closing the shutter239, supply of controlled particles 31 can be started and stopped.

In this example, in the storage mechanism 1, the controlled particles 31pass through the orifice 238 and fall outside by their self-weight.Hence, the controlled particles 31 are not excessively packed down. Thatis, the controlled particles 31 are supplied without collapse. Thus, itis possible to prevent controlled particles 31 with altered propertiesfrom being supplied from the constant supply mechanism 2. Hence, thecontrolled particles 31 with the aforementioned properties such as meancompressive fracture strength, circularity, and angle of repose beingadjusted can be directly supplied, thereby stabilizing the supply. Thus,stable supply on target can be achieved without stacking.

Furthermore, a plurality of controlled particles 31 are supplied nearlysimultaneously and continuously through the orifice 238. That is, in theaerosolation mechanism 4, numerous controlled particles 31 are alwayssupplied continuously, and the supply quantity of the controlledparticles 31 is averaged in terms of time. Thus, in the aerosolationmechanism 4, a constant quantity of controlled particles 31 is alwaysstably supplied, and hence an aerosol having a constant fine particleconcentration can be stably generated.

Controlled particles having a certain bonding strength or more and acontrolled shape can be favorably used in the aforementioned constantsupply mechanisms, because the controlled particle is not broken ordisaggregated in the supply process.

Next, the aerosolation mechanism 4 is described with reference toexamples.

FIG. 31 is a schematic view for illustrating a first example of theaerosolation mechanism.

The aerosolation mechanism 4 a includes a supply port 1502 for squirtingcontrolled particles 31 with a gas, an impact plate 1504 provided infront thereof and serving as a mechanical barrier, and an ejection port1505.

The controlled particle 31 squirted from the supply port 1502 receivesan impact force when colliding with the impact plate 1504. This impactforce disaggregates the controlled particle 31 into primary particles30P, or aggregate particles 30Q with several primary particles 30Paggregated therein, which are dispersed in the gas to form an aerosol32. The aerosol 32 is carried with the gas flow and ejected from theejection port 1505.

Furthermore, by rotating the impact plate 1504, the motion vector of thecontrolled particle 31 at the collision point is generally opposed tothe motion vector of the spray of the aerosol 32. Hence, the impactforce on the controlled particle 31 can be increased. Consequently, thefine particle concentration in the aerosol 32 can be made morehomogeneous.

The material of the impact plate 1504 is preferably hard, and canillustratively be a ceramic, such as alumina, silicon carbide, siliconnitride, and aluminum nitride. The speed of collision with the impactplate 1504 only needs to be such that the controlled particle 31 issufficiently disaggregated, and is preferably slower than the speed atwhich a structure is formed on the surface of the impact plate 1504 bythe impact of collision.

Ideally, this mechanical impact completely disaggregates the controlledparticle 31 into primary particles 30P contributing to structureformation in the aerosol deposition method, and the structure formationefficiency is maximized in this case. However, actually, disaggregationonly needs to be roughly completed so as to maintain the structureformation efficiency which allows structure formation with industriallyapplicability. This can be determined from the film thickness which canbe formed per unit time.

FIG. 32 is a schematic view for illustrating a second example of theaerosolation mechanism.

The aerosolation mechanism 4 b includes a supply port 1502 for supplyingcontrolled particles 31, a collision plate 1504 a provided in frontthereof and serving as a mechanical barrier, and an ejection port 1505.A gas supply port 1507 is provided generally parallel to the collisionplate 1504 a, and the ejection port 1505 is provided in front of the gassupply port 1507.

The controlled particle 31 is supplied on the gas flow, collides withthe collision plate 1504 a, and is thereby disaggregated into primaryparticles 30P, or aggregate particles 30Q with several primary particles30P aggregated therein. By squirting a gas from the gas supply port 1507to the collision location, the green compact adhered to the collisionplate 1504 a can be blown off, and a uniform aerosol can be generated.

FIG. 33 is a schematic view for illustrating a third example of theaerosolation mechanism.

The aerosolation mechanism 4 c includes a supply port 1502 for supplyingcontrolled particles 31, a gas supply port 1507 a for forming a pressurebarrier in front thereof, and an ejection port 1505. The gas supply port1507 a is provided generally coaxial with the conduit provided with theejection port 1505.

The controlled particle 31 is supplied on the gas flow and collides withthe pressure barrier formed by the gas supply port 1507 a. At this time,the controlled particle 31 is subjected to a shear force, and hencedisaggregated into primary particles 30P, or aggregate particles 30Qwith several primary particles 30P aggregated therein. Then, by the gassquirted from the gas supply port 1507 a, a uniform aerosol is formed.

FIG. 34 is a schematic view for illustrating a fourth example of theaerosolation mechanism.

The aerosolation mechanism 4 d includes a site 1506 having a large flowchannel diameter and a site 1508 having a small flow channel diameter,which are alternately provided along the flow channel of the aerosol.Thus, the gas is compressed at the site 1508 having a small flow channeldiameter, and expanded at the site 1506 having a large flow channeldiameter. Repetition of such compression and expansion causes a shearforce to act on the controlled particles 31 contained in the aerosol.This shear force disaggregates the controlled particle 31 into primaryparticles 30P, or aggregate particles 30Q with several primary particles30P aggregated therein.

The number of sites 1506 having a large flow channel diameter and thenumber of sites 1508 having a small flow channel diameter are notlimited to those illustrated, but can be suitably modified in accordancewith the size, strength and the like of the controlled particle 31supplied.

FIG. 35 is a schematic view for illustrating a fifth example of theaerosolation mechanism.

The aerosolation mechanism 4 e includes a first gas supply port 1507 band a second gas supply port 1507 c. The first gas supply port 1507 band the second gas supply port 1507 c are provided so that their axislines intersect each other.

Hence, controlled particles 31 supplied from the first gas supply port1507 b and the second gas supply port 1507 c can be collided with eachother. This collision disaggregates the controlled particles 31 intoprimary particles 30P, or aggregate particles 30Q with several primaryparticles 30P aggregated therein. In addition, this example can avoidcollision of controlled particles 31 with the wall surface, and has anadvantage of being less prone to contamination.

Controlled particles having a certain bonding strength or more and acontrolled shape can be used in the aforementioned aerosolationmechanisms. Then, the controlled particles are easily disaggregated toproduce an aerosol being rich in primary particles. Hence, theaforementioned aerosolation mechanisms are suitable for compositestructure formation.

The invention claimed is:
 1. A composite structure formation method based on an aerosol deposition method by which an aerosol with brittle material fine particles dispersed in a gas is sprayed toward a substrate to form a structure made of the brittle material fine particles, the composite structure formation method comprising the steps of: storing a plurality of pre-formed controlled particles in a storage mechanism, each of the controlled particles consists essentially of a plurality of the brittle material fine particles which have been intentionally packed together, each of the brittle material fine particles in each said controlled particle is not chemically bonded together with the other brittle material fine particles in the controlled particle, the controlled particles being formed by using the fine particles whose mean primary particle diameter is 0.1 μm or more and 5 μm or less, the controlled particles have a mean circle-equivalent diameter of 20 μm or more and 500 μm or less, and each of the controlled particles has a mean compressive fracture strength of 0.47 MPa or less; supplying the controlled particles from the storage mechanism to an aerosolation mechanism constantly; disaggregating the supplied controlled particles into a plurality of the fine particles in the aerosolation mechanism to form an aerosol in which an entire contents of the controlled particles including the fine particles are dispersed in the gas; and spraying all of the fine particles in the aerosol toward the substrate to form a composite structure of the structure and the substrate, wherein the controlled particles are controlled so that bonding strength between the fine particles includes a mean compressive fracture strength sufficient to substantially avoid disaggregation during the supply step, but which permits the controlled particles to be substantially completely disaggregated in the disaggregation step.
 2. The composite structure formation method according to claim 1, further comprising the step of: mixing the controlled particles with a gas introduced from a gas supply mechanism to produce a solid-gas mixed phase flow; and supplying the solid-gas mixed phase flow to the aerosolation mechanism.
 3. The composite structure formation method according to claim 1, wherein the mean compressive fracture strength is controlled by manufacturing the controlled particles by adding the fine particles with at least one of water and a binder.
 4. The composite structure formation method according to claim 1, wherein the controlled particles are disaggregated by mechanical impact applied in the aerosolation mechanism.
 5. The composite structure formation method according to claim 1, wherein the mean compressive fracture strength of the controlled particles is 0.34 MPa or less.
 6. The composite structure formation method according to claim 1, wherein the mean compressive fracture strength of the controlled particles is 0.015 MPa or more.
 7. The composite structure formation method according to claim 1, wherein the controlled particles has a mean circularity of 0.65 or more.
 8. The composite structure formation method according to claim 1, wherein the controlled particles have a D10 of 6.6 μm or more.
 9. The composite structure formation method according to claim 1, wherein the controlled particles have a particle size distribution deviation ratio of 0.59 or less.
 10. The composite structure formation method according to claim 1, wherein the controlled particles have an angle of repose of 48 degrees or less. 